Murali R, Lalitha V, Subramanian E, Parthasarathy R
Int J Pept Protein Res. 1986 Feb;27(2):160-4. doi: 10.1111/j.1399-3011.1986.tb01806.x.
The dipeptide, (DL)-alanyl-(DL)-norvaline, crystallizes in the monoclinic space group P2(1)/c, with a = 12.559(2)A, b = 5.265(1), c = 16.003(3), beta = 103.53(2) degrees, Z = 4. The structure was solved by direct methods and refined to an R-value of 0.054 for 871 reflections with I greater than 2 sigma. The molecule exists as a zwitterion in the crystal. The peptide unit is trans and shows significant deviations from planarity (delta omega = 12.4 degrees). The peptide backbone adopts an extended conformation. The unit cell contains D-Ala-L-norval and its enantiomer. The molecular conformation and packing features show a striking resemblance to those for D-Ala-L-Met (1), and leads to the speculation that norvaline might act as an analog of methionine.
二肽（DL）-丙氨酰-（DL）-正缬氨酸以单斜空间群P2(1)/c结晶，a = 12.559(2)埃，b = 5.265(1)，c = 16.003(3)，β = 103.53(2)度，Z = 4。通过直接法解析结构，并对871个I大于2σ的反射进行精修，R值为0.054。该分子在晶体中以两性离子形式存在。肽单元为反式，且明显偏离平面性（δω = 12.4度）。肽主链呈伸展构象。晶胞包含D-丙氨酰-L-正缬氨酸及其对映体。分子构象和堆积特征与D-丙氨酰-L-甲硫氨酸（1）的极为相似，从而推测正缬氨酸可能作为甲硫氨酸的类似物起作用。
